release of classified documents that assess Israel’s plans to attack Iran.

 The US government is investigating an unauthorised release of classified documents that assess Israel’s plans to attack Iran.

The US House speaker, Mike Johnson, confirmed the investigation in remarks to CNN’s State of the Union programme on Sunday, saying the leak was very concerning.

“There’s some serious allegations being made there,” the Republican from Louisiana said. “The investigation’s under way, and I’ll get a briefing on that in a couple of hours.”

A US official told the Associated Press the documents in question appeared to be legitimate, but the Guardian was not immediately able to verify their authenticity.

Protester with face covering holding a banner with Sinwar’s face.

Why Sinwar’s ‘warrior death’ will win him martyr status in Gaza and beyond

Read more

The documents are attributed to the US Geospatial-Intelligence Agency and National Security Agency. They are written in a style similar to documents previously leaked from the Pentagon, using classifications familiar to the national security community.

The first document has the title “Israel: air force continues preparations for strike on Iran and conducts a second large-force employment exercise” and the second “Israel: defense forces continue key munitions preparations and covert UAV activity almost certainly for a strike on Iran”. Both are dated 16 October and were first leaked a day later.

In general terms, they note that Israel was still positioning military assets as of the middle of last week to conduct a military strike in response to Iran’s ballistic missile attack on 1 October.

Based on monitoring from satellite imagery and other geospatial intelligence, they focus on Israeli preparations relating to air-launched ballistic missiles, refuelling aircraft and covert long-range drone surveillance in Iran and elsewhere in the Middle East.

That could imply that Israel was planning a long-range missile response to Iran’s attack, described at one point as similar to the long-range strikes it conducted against the Houthis in Yemen on 29 September.

It appears to reflect an effort by the US and its closest partners to independently monitor Israel’s plans to attack Iran, though they do not predict its scale or scope. No potential targets in Iran were mentioned in the documents.

The two documents appear to represent a snapshot in time, and are likely to represent the outcome of continuous monitoring. At one point, it is said there is no evidence that Israel is planning to use a nuclear weapon.

They refer to preparations to use long-range Rocks missiles, made by the Israeli company Rafael, which are designed to destroy targets above and below ground. Another ballistic system called Golden Horizon is also referred to, but no system of that name is publicly known.

Israeli media speculated that could refer to Blue Sparrow missiles, which have a range of about 1,200 miles (2,000km) and are thought to have been used in Israel’s limited strike against Iran in April in response to an previous attack by Tehran. Israel keeps elements of its long-range missile programme secret to avoid its enemies becoming fully aware of its capability.

Many elements in the two documents are described as shareable within the Five Eyes intelligence network made up of the US, the UK, Canada, New Zealand and Australia. Others are marked as only shareable between the US and the UK.

The documents, which are marked top secret, were posted to the Telegram messaging app and first reported by CNN and Axios.

US officials spoke on condition of anonymity because they were not authorised to discuss the matter publicly. The investigation was also examining how the documents were obtained – including whether it was an intentional leak by a member of the US intelligence community or obtained by another method, like a hack – and whether any other intelligence information was compromised, one of the officials said.

As part of that investigation, officials were working to determine who had access to the documents before they were posted, the official added.

The US has urged Israel to take advantage of its elimination of Hamas leader Yahya Sinwar and press for a ceasefire in Gaza, and has likewise urgently cautioned Israel not to further expand military operations in the north in Lebanon and risk a wider regional war. However, Israel’s leadership has repeatedly stressed it will not let Iran’s missile attack go unanswered.

In a statement, the Pentagon said it was aware of the reports of the documents but did not have further comment.

Johnson on Sunday said he spoke with the Israeli prime minister, Benjamin Netanyahu – referring to him as “my friend” – and explained how he had made it a point “to encourage him”. He also said there would be “a classified level briefing, and then others, but we’re following it closely”.

The Israeli military did not immediately respond to a request for comment over the leak of the two documents. Israeli security officials were expected to meet on Sunday evening.

The documents first appeared online Friday via a channel on Telegram, claiming they had been leaked by someone in the US intelligence community, then later the US Department of Defense. The information appeared entirely gathered through the use of satellite image analysis.

One of the two documents resembled the style of other material from the US National Geospatial-Intelligence Agency leaked by Jack Teixeira, an air national guardsman who pleaded guilty in March to leaking highly classified military documents about Russia’s war on Ukraine and other national security secrets.

Analytical intelligence documents have a wide distribution within the US national security apparatus, but the Pentagon has been engaged in an effort to clamp down on leaks by restricting them after Teixeira leaked dozens of slides on Discord, a social media site popular with gamers, in April 2023.

The Telegram channel involved in the leak identifies itself as being based in Tehran, Iran’s capital. It previously published memes featuring Iran’s supreme leader, Ayatollah Ali Khamenei, and material in support of Tehran’s self-described “axis of resistance”, which includes Middle East militant groups armed by the Islamic Republic.

The Associated Press contributed to this report

This is what we are up against 

In a time of increasing misinformation spread by bad actors, extremist media and politicians like Donald Trump pushing the strength of democracy to its limits, real, reliable journalism has never been more important – and we’re proud to be able to share ours widely thanks to the generous support of readers like you in Pakistan.

The Guardian believes that access to trustworthy information is vital for democracy. By helping fund the Guardian today, you can play a vital role in combating the bad faith and self-interest of those who spread lies to undermine democracy and stoke political division around the globe.

If you can, please support us on a monthly basis. It takes less than a minute to set up, and you can rest assured that you’re making a big impact every single month in support of open, independent journalism. Thank you.